The standard size of masonry bricks is 20 cm x 10 cm x 10 cm. This is the most common size of brick used in construction, and it is available in a variety of materials, including concrete, clay, and stone. Bricks of this size are easy to handle and stack, and they can be used to create a variety of structures, from simple walls to complex buildings.
Option A is incorrect because it is the size of a standard concrete masonry unit (CMU). CMUs are larger and heavier than bricks, and they are typically used in foundations and other load-bearing applications.
Option B is incorrect because it is the size of a standard clay brick. Clay bricks are smaller and lighter than CMUs, and they are typically used in non-load-bearing applications, such as interior walls and facings.
Option C is incorrect because it is the size of a standard stone brick. Stone bricks are the largest and heaviest type of brick, and they are typically used in high-end construction applications.
Option D is incorrect because it is not a standard size of brick.